30.1.51 ExpDec2

Function

$y=y_0+A_1e^{-x/t_1}+A_2e^{-x/t_2}$

Two-phase exponential decay function with time constant parameters.

Number: 5

Names: y0, A1, t1, A2, t2

Meanings: y0 = offset, A1 = amplitude, t1 = time constant, A2 = amplitude, t2 = time constant

Lower Bounds: none

Upper Bounds: none

Note: different initial parameters are used for t1 and t2 so as to make sure t2 > t1 in the fitting results.

Individual decay rate:

k1=1/t1

k2=1/t2

Individual half life:

thalf1=t1*ln(2)

thalf2=t2*ln(2)

Note: Half life is usually denoted by the symbol $t_{1/2}$ by convention.

nlf_expdec2(x,y0,A1,t1,A2,t2)

FITFUNC\EXPDEC2.FDF